<?php
function md5_of_dir($folder) {
	$dircontent = scandir($folder); 
	$ret='';
	foreach($dircontent as $filename) {
		if ($filename != '.' && $filename != '..') {
			if (filemtime($folder.$filename) === false) return false;
			$ret.=date("YmdHis", filemtime($folder.$filename)).$filename;
		}
	}
	return md5($ret);
} 
function delete_old_md5s($folder) {
	$olddate=time()-3600;
	$dircontent = scandir($folder);
	foreach($dircontent as $filename) {
		if (strlen($filename)==32 && filemtime($folder.$filename) && filemtime($folder.$filename)<$olddate) unlink($folder.$filename);
	}
}
